Conformable Microporous Fiber and Woven Fabrics Containing Same

ABSTRACT

Expanded polytetrafluoroethylene (ePTFE) monofilament fibers and woven fabrics formed from the ePTFE fibers are provided. The ePTFE fibers have a substantially rectangular configuration, a density less than about 1.0 g/cc, and an aspect ratio greater than 15. Additionally, the ePTFE fibers are microporous and have a node and fibril structure. The ePTFE fiber may be woven into a fabric without first twisting the fiber. A polymer membrane and/or a textile may be laminated to the woven fabric to produce a laminated article. The ePTFE woven fabric simultaneously possesses high moisture vapor transmission (highly breathable) and high water entry pressure (water resistant). The woven fabric is quiet, soft, and drapable, making it especially suitable for use in garments, gloves and footwear applications. Treatments may be provided to the surface of the ePTFE fiber and/or the woven fabric to impart one or more desired functionality, such as, for example, oleophobicity.

FIELD OF THE INVENTION

The present invention relates generally to conformable microporousfibers, and more specifically, to conformable microporous fibers havinga node and fibril structure that are highly breathable. Woven fabricscontaining the conformable microporous fibers are also provided.

BACKGROUND OF THE INVENTION

Waterproof, breathable garments are well-known in the art. Thesegarments are often constructed from multiple layers in which each layeradds a certain functionality. For example, a garment could beconstructed using an outer textile layer, a waterproof, breathable filmlayer, and an inner textile layer. The outer and inner textile layersprovide protection to the breathable film layer. However, the additionof outer and inner fabric layers not only adds weight to an article ofapparel, it also results in materials having the potential for a highwater pick-up on the outer surface. The pick-up of water by the outerfabric layer permits for thermal conductivity and the passage of thetemperature of the water through the fabric and to the wearer. This maybe detrimental in cases where the wearer is in a cold environment andthe cold is transported to the body of the wearer. In addition, waterpick-up may lead to condensation on the inside of the garment, makingthe wearer feel wet. Further, the color of the outer fabric may becomediscolored or darken upon water pick-up, thus reducing the aestheticappearance of the garment. Also, depending on the outer fabric, theremay be a long dry time associated with the fabric itself, forcing thewearer to endure the disadvantages associated with the water pick-up fora longer time. Additionally, the fibers associated with conventionalfabrics used in the inner and outer layer are constructed ofmultifilament fibers, which permit water and/or contaminants between thefilaments. Additionally, because multifilament fibers are loosely packedfor breathability in the fabric, water can undesirably fill the spacebetween the fibers.

Thus, there exists a need in the art for a fiber to make woven fabricsfor use in garments that is highly breathable, has a high water entrypressure, and has a low water pick-up.

SUMMARY OF THE INVENTION

It is an object of the present invention to provide a woven fabric thatincludes warp and weft expanded polytetrafluoroethylene (ePTFE) fibersthat have a microporous structure of nodes and fibrils, where the widthof the ePTFE fiber is greater than the width allotted to the ePTFE fiberbased on the end count or pick count of the woven fabric. Thisdifference in width causes the ePTFE fiber to fold upon itself toconform to the weave spacing provided between the crossovers of the warpand weft fibers. The ePTFE fibers may be monofilament fibers. The ePTFEfibers may have a density less than about 1.2 g/cm³, an aspect ratiogreater than about 15, and a substantially rectangular cross sectionalconfiguration. Advantageously, the ePTFE woven fabric possesses both ahigh moisture vapor transmission and a high water entry pressure. Inparticular, the woven fabric has a moisture vapor transmission rategreater than about 10,000 g/m²/24 hours and a water entry pressuregreater than about 1 kPa. Thus, the woven fabric is highly breathable,has a low water pick-up, and is highly water resistant.

It is another object of the present invention to provide a woven fabricthat includes a plurality of warp and weft fibers where each of the warpand weft fibers include expanded polytetrafluoroethylene fibers thathave a density less than about 1.2 g/cm³ and a substantially rectangularcross sectional configuration. The ePTFE fibers may be monofilamentfibers. At least one of the warp and weft ePTFE fibers may have anaspect ratio greater than about 15. In at least one exemplaryembodiment, the width of the ePTFE fibers is greater than the number ofpicks per inch of the woven fabric. Further, the woven fabric has anaverage stiffness less than about 300 g and a water pick-up less than 30gsm. The warp fibers and weft fibers may have a fluoroacrylate coatingto render the woven fabric oleophobic. A fluoropolymer membrane, orother functional membranes or protective layer, may be affixed to thewoven fabric on a side opposing the fluoroacrylate coating. In someembodiments, a textile may be affixed to the fluoropolymer membrane toform a laminated article. In other embodiments, a fluoropolymer membraneand/or a textile may be affixed to the woven fabric without theapplication of a coating.

It is a further object of the invention to provide a woven fabric thatincludes warp and weft fibers of expanded polytetrafluoroethylene fibershaving an aspect ratio greater than about 15 and a substantiallyrectangular cross-section configuration. The woven fabric has a waterentry pressure greater than about 1 kPa and a moisture vaportransmission rate greater than about 10,000 g/m²/24 hours. The ePTFEfibers may be monofilament fibers. Additionally, the fibers may have apre-weaving thickness less than about 100 microns, a pre-weaving widthless than about 4.0 mm, and a pre-weaving density less than about 1.0g/cm³. Further, the ePTFE fibers have a node and fibril structure wherethe nodes are interconnected by fibrils that define passageways throughthe fiber. The fibrils may have a length from about 5 microns to about120 microns.

It is yet another object of the invention to provide a woven fabric thatincludes warp and weft fluoropolymer fibers where at least one of thewarp and weft fluoropolymer fibers is in a folded configuration along alength of the fiber. In at least one exemplary embodiment, thefluoropolymer fibers are ePTFE fibers that have a density less thanabout 1.2 g/cm³ and have a substantially rectangular configuration. Inexemplary embodiments, the ePTFE fibers have a pre-weaving density lessthan about 0.85 g/cm³. The woven fabric has a moisture vaportransmission rate greater than about 10,000 g/m²/24 hours and a waterentry pressure greater than about 1 kPa. In addition, the woven fabrichas a tear strength of at least 30 N and an average stiffness of lessthan about 300 g. In at least one exemplary embodiment, the width of thefluoropolymer fiber is greater than the width allotted to thefluoropolymer fiber in the woven fabric based on the end count or pickcount of the woven fabric.

It is also an object of the present invention to provide a woven fabricthat includes conformable warp and weft fluoropolymer fibers where atleast one of the warp and weft fibers have a node and fibril structurethat form passageways through the fiber. The fibrils may have a lengthfrom about 5 microns to about 120 microns. In at least one embodiment,the fluoropolymer fibers are ePTFE fibers that have a pre-weavingdensity less than about 1.0 g/cm³, and in other embodiments, less thanabout 0.85 g/cm³. The conformability of the fiber permits the fiber tocurl and/or fold upon itself to conform to weave spacing providedbetween the crossovers of the warp and weft fibers in a wovenconfiguration. Additionally, a functional membrane or protective layer,such as a fluoropolymer membrane, may be affixed to the ePTFE wovenfabric. In some embodiments, a textile is affixed to the fluoropolymermembrane to form a laminated article.

It is yet another object of the present invention to provide amonofilament fiber that includes expanded polytetrafluoroethylene. TheePTFE monofilament fiber has a density less than or equal to 1.0 g/cm³,a thickness less than about 100 microns, a width less than about 4.0 mm,an aspect ratio greater than about 15, and a substantially rectangularcross-section configuration. In addition, the fiber has a tenacitygreater than about 1.6 cN/dtex and a break strength of at least about1.5 N. The ePTFE monofilament fiber may have thereon a fluoroaciylatecoating, or other oleophobic treatment. Additionally, the ePTFEmonofilament fibers have a node and fibril configuration where the nodesand fibrils define passageways through the fiber. The fibril length maybe from about 5 microns to about 120 microns. Further, the ePTFEmonofilament fiber is conformable such that in a woven configuration,the ePTFE monofilament fiber folds upon itself to conform to weavespacing provided between the crossovers of the warp and weft fibers inthe woven fabric. Such ePTFE monofilament fibers are utilized inexemplary embodiments of the invention to form woven fabrics that mayultimately be used in an article that demands high moisture vaportransmission and high water entry pressure (i.e., high breathability andhigh resistance to water).

It is an advantage of the present invention that even when the ePTFEfiber is tightly woven, the ePTFE woven fabric is highly breathable andhas a high water entry pressure.

It is another advantage of the present invention that the ePTFE fibersmay be tightly woven into a woven fabric that is highly breathable yetpossesses a low air permeability.

It is also an advantage of the present invention that the woven fabricis quiet, soft, and drapable.

It is yet another advantage of the present invention that the highaspect ratio of the ePTFE fibers enables low weight per area fabric,easier and more efficient reshaping, and can achieve high waterresistance in a woven fabric with less picks and ends per inch.

It is a feature of the present invention that the ePTFE fibers curland/or fold upon themselves to conform to the weave spacing providedbetween the crossovers of the warp and weft fibers in the woven fabric.

It is also a feature of the present invention that woven fabricsconstructed from the ePTFE fibers have a flat or substantially flatweave and a corresponding smooth surface.

It is another feature of the present invention that the ePTFE fibershave a substantially rectangular cross-section configuration,particularly prior to weaving.

BRIEF DESCRIPTIONS OF FIGURES

The advantages of this invention will be apparent upon consideration ofthe following detailed disclosure of the invention, especially whentaken in conjunction with the accompanying drawings wherein:

FIG. 1 is a scanning electron micrograph (SEM) of the top surface of anexemplary ePTFE fiber taken at 1000× magnification according to oneexemplary embodiment of the invention;

FIG. 2 is a scanning electron micrograph of a side of the ePTFE fiberdepicted in FIG. 1 taken at 1000× magnification;

FIG. 3 is scanning electron micrograph of the top surface of a 2/2 woventwill fabric of the fiber depicted in FIG. 1 taken at 150×magnification;

FIG. 4 is a scanning electron micrograph of a side of the woven fabricdepicted in FIG. 3 taken at 150× magnification;

FIG. 5 is a scanning electron micrograph of the top surface of the 2/2woven twill fabric depicted in FIG. 3 having thereon a fluoroacrylatecoating taken at 150× magnification;

FIG. 6 is a scanning electron micrograph of a side of the woven fabricdepicted in FIG. 5 taken at 150× magnification;

FIG. 7 is a scanning electron micrograph of the top surface of the 2/2woven twill fabric illustrated in FIG. 5 having laminated thereto anePTFE membrane taken at 150× magnification;

FIG. 8 is a scanning electron micrograph of a side of the articledepicted in FIG. 7 taken at 100× magnification;

FIG. 9 is a scanning electron micrograph of a side of the fabricdepicted in FIG. 7 taken at 1000× magnification;

FIG. 10 is a scanning electron micrograph of the top surface of thewoven fabric illustrated in FIG. 5 laminated to a textile taken at 150×magnification according to another exemplary embodiment of theinvention;

FIG. 11 is a scanning electron micrograph of a side of the articledepicted in FIG. 10 taken at 100× magnification;

FIG. 12 is a scanning electron micrograph of a side of the articledepicted in FIG. 10 taken at 500× magnification;

FIG. 13 a scanning electron micrograph of the top surface of a wovenfabric having laminated thereto an ePTFE membrane and a textileaccording to an exemplary embodiment of the invention taken at 150×magnification;

FIG. 14 is a scanning electron micrograph of a side of the articledepicted in FIG. 13 taken at 100× magnification;

FIG. 15 is a scanning electron micrograph of a side of the articledepicted in FIG. 13 taken at 300× magnification;

FIG. 16 is a scanning electron micrograph of the top surface of a plainwoven fabric according to one exemplary embodiment of the inventiontaken at 150× magnification;

FIG. 17 is a scanning electron micrograph of a side of the fabricdepicted in FIG. 16 taken at 250× magnification;

FIG. 18 is scanning electron micrograph of the top surface of the plainwoven fabric illustrated in FIG. 16 having thereon a fluoroacrylatecoating taken at 150× magnification;

FIG. 19 is a scanning electron micrograph of a side of the woven fabricdepicted in FIG. 18 taken at 250× magnification;

FIG. 20 is a scanning electron micrograph of the top surface of thewoven fabric depicted in FIG. 16 having laminated thereto an ePTFEmembrane and a textile taken at 150× magnification according to anexemplary embodiment of the invention;

FIG. 21 is a scanning electron micrograph of a side view of the articledepicted in FIG. 20 taken at 250× magnification;

FIG. 22 is a scanning electron micrograph of the top surface of anexemplary ePTFE fiber taken at 1000× magnification according to anotherexemplary embodiment of the invention;

FIG. 23 is a scanning electron micrograph of a side of the ePTFE fiberdepicted in FIG. 22 taken at 1000× magnification;

FIG. 24 is a scanning electron micrograph of the top surface of a 2/2twill fabric of the ePTFE fiber depicted in FIG. 22 taken at 150×magnification;

FIG. 25 is a scanning electron micrograph of a side of the fabricdepicted in FIG. 24 taken at 200× magnification;

FIG. 26 is a scanning electron micrograph of the top surface of thewoven twill fabric depicted in FIG. 16 having thereon a fluoroacrylatecoating taken at 150× magnification;

FIG. 27 is a scanning electron micrograph of a side of the fabricdepicted in FIG. 26 taken at 200× magnification;

FIG. 28 is a scanning electron micrograph of the top surface of anexemplary ePTFE fiber according to a further embodiment of the inventiontaken at 1000× magnification;

FIG. 29 is a scanning electron micrograph of a side of the fiberdepicted in FIG. 28 taken at 1000× magnification;

FIG. 30 is a scanning electron micrograph of the top surface of a 2/2twill woven fabric of the ePTFE fiber illustrated in. FIG. 26 taken at150× magnification;

FIG. 31 is a scanning electron micrograph of a side of the fabricdepicted in FIG. 30 taken at 150× magnification;

FIG. 32 is a scanning electron micrograph of the top surface of a highdensity comparative ePTFE fiber taken at 1000× magnification;

FIG. 33 is a scanning electron micrograph of a side of a woven fabric ofthe fiber depicted in FIG. 32 taken at 1000× magnification;

FIG. 34 is a scanning electron micrograph of the top surface of a 2/2twill woven comparative fabric utilizing a comparative high densityePTFE fiber taken at 150× magnification;

FIG. 35 is a scanning electron micrograph of a side of the fabricdepicted in FIG. 34 taken at 150× magnification;

FIG. 36 is a scanning electron micrograph of a top surface of anexemplary fiber taken at 1000× magnification;

FIG. 37 is a scanning electron micrograph of a side of the fiberdepicted in FIG. 36 taken at 1000× magnification;

FIG. 38 is a scanning electron micrograph of the top surface of a wovenfabric of the fiber shown in FIG. 36 taken at 150× magnification;

FIG. 39 is a scanning electron micrograph of a side of the fabricdepicted in FIG. 38 taken at 150× magnification;

FIG. 40 is a schematic illustration depicting a side view of exemplaryfibers folding into a folded configuration to fit into the spaceallotted to the fiber in the woven configuration;

FIG. 41 is a schematic illustration depicting a top view of exemplaryfibers folding into a folded configuration to fit into the spaceallotted to the fiber in the woven configuration;

FIG. 42 is a scanning electron micrograph of the top surface of anexemplary plain weave fabric with a 40×40 thread count taken at 150×magnification;

FIG. 43 is a scanning electron micrograph of a side of the woven fabricdepicted in FIG. 42 taken at 150× magnification;

FIG. 44 is a scanning electron micrograph of a side of the woven fabricdepicted in FIG. 42 taken at 300× magnification;

FIG. 45 is a scanning electron micrograph of a side of the woven fabricdepicted in FIG. 42 taken at 400× magnification;

FIG. 46 is a scanning electron micrograph of the top surface of acomparative non-porous ePTFE fiber taken at 1000× magnification;

FIG. 47 is a scanning electron micrograph of a side of the fiberdepicted in FIG. 46 taken at 1000× magnification;

FIG. 48 is a scanning electron micrograph of a woven fabric of the fiberdepicted in FIG. 46 taken at 150× magnification;

FIG. 49 is a scanning electron micrograph of a side of the woven fabricof FIG. 48 taken at 150× magnification;

FIG. 50 is a scanning electron micrograph of the top surface of acomparative woven fabric of a comparative high density ePTFE fiber takenat 150× magnification;

FIG. 51 is a scanning electron micrograph of a side surface of the wovenfabric illustrated in FIG. 50 taken at 150× magnification; and

FIG. 52 is a scanning electron micrograph illustrating gap widthmeasurements.

DEFINITIONS

The terms “monofilament fiber” and “monofilament ePTFE fiber” as usedherein are meant to describe an ePTFE fiber that is continuous orsubstantially continuous in nature which may be woven into a fabric.

The terms “fiber” and “ePTFE fiber” as used herein are meant to includemonofilament ePTFE fibers as well as a plurality of monofilament ePTFEfibers, such as, for example, fibers in a side-by-side configuration, ina bundled configuration, or in a twisted or otherwise intermingled form.

The term “conformable” and “conformable fiber” as used herein are meantto describe fibers that are capable of curling and/or folding uponthemselves to conform to weave spacing provided between the crossoversof the warp and weft fibers and as determined by the number of picks perinch and/or ends per inch of the warp and weft fibers.

“High water entry pressure” as used herein is meant to describe a wovenfabric with a water entry pressure greater than about 1 kPa.

The phrase “low water pick-up” as used herein is meant to denote a wovenfabric having a water pick-up less than about 50 gsm.

The term “substantially rectangular configuration” as used herein ismeant to denote that the conformable, microporous fibers have arectangular or nearly rectangular cross section, with or without arounded or pointed edge (or side).

DETAILED DESCRIPTION OF THE INVENTION

The present invention relates to conformable microporous fibers having anode and fibril structure and woven fabrics produced therefrom. Apolymer membrane and/or a textile may be laminated to the woven fabricto produce a laminated article. The woven fabric concurrently possesseshigh moisture vapor transmission (i.e., highly breathable), high waterentry pressure, and low water pick-up. The woven fabric can becolorized, such as, for example, by printing. In addition, the wovenfabric is quiet, soft, and drapable, making it especially suitable foruse in garments, gloves, and in footwear applications. It is to be notedthat the terms “woven fabric” and “fabric” may be used interchangeablyherein. In addition, the terms “ePTFE fiber” and “fiber”, may beinterchangeably used within this application.

The conformable fibers have a node and fibril structure where the nodesare interconnected by fibrils, the space between which definespassageways through the fibers. Also, the conformable fibers aremicroporous. Microporous is defined herein as having pores that are notvisible to the naked eye. The node and fibril structure within the fiberpermits the fiber, and fabrics woven from the fiber, to be highlybreathable and allow for the penetration of colorants and oleophobiccompositions. Also, the matrix provided by the nodes and fibrils allowsfor the inclusion of desired fillers and/or additives.

It is to be appreciated that with respect to the conformable,microporous fibers; reference is made herein with respect to expandedpolytetrafluorethylene (ePTFE) fibers for ease of discussion. However,it is to be understood that any suitable conformable fluoropolymerhaving a node and fibril structure may be used interchangeably withePTFE as described within this application. Non-limiting examples offluoropolymers include, but are not limited to, expanded PTFE, expandedmodified PTFE, expanded copolymers of PTFE, fluorinated ethylenepropylene (FEP), and perfluoroalkoxy copolymer resin (PFA). Patents havebeen granted on expandable blends of PTFE, expandable modified PTFE, andexpanded copolymers of PTFE, such as, but not limited to, U.S. Pat. No.5,708,044 to Branca; U.S. Pat. No. 6,541,589 to Baillie; U.S. Pat. No.7,531,611 to Sabol et al.; U.S. patent application Ser. No. 11/906,877to Ford; and U.S. patent application Ser. No. 12/410,050 to Xu et al.The fibril length of the ePTFE fibers ranges from about 5 microns toabout 120 microns, from about 10 microns to about 100 microns, fromabout 15 microns to about 80 microns, or from about 15 microns to about60 microns.

Additionally, the ePTFE fibers have a substantially rectangularconfiguration. At least FIGS. 4, 6, 12, 14, 17, 19, 21, 27, 30, 39, 43,44, 45 of this application depict exemplary ePTFE fibers havingsubstantially rectangular configurations. As used herein, the term“substantially rectangular configuration” is meant to denote that thefibers have a rectangular or nearly rectangular cross section. That is,the ePTFE fibers have a width that is greater than its height(thickness). It is to be noted that the fibers may have a rounded orpointed edge (or side). Unlike conventional fibers that must be twistedprior to weaving, the ePTFE fibers can be woven while in a flat statewithout having to first twist the ePTFE fiber. The ePTFE fibers may beadvantageously woven with the width of the fiber oriented so that itforms the top surface of the woven fabric. Thus, woven fabricsconstructed from the inventive ePTFE fibers have a flat or substantiallyflat weave and a corresponding smooth surface. The smooth, planarsurface of the fabric enhances the softness of the woven fabric.

In addition, the ePTFE fibers used herein have a low density. Morespecifically, the fibers have a pre-weaving density less than about 1.0g/cm³. In exemplary embodiments, the fibers have a pre-weaving densityless than about 0.9 g/cm³, less than about 0.85 g/cm³, less than about0.8 g/cm³, less than about 0.75 g/cm³, less than about 0.7 g/cm³, lessthan about 0.65 g/cm³, less than about 0.6 g/cm³, less than about 0.5g/cm³, less than about 0.4 g/cm³, less than about 0.3 g/cm³, or lessthan about 0.2 g/cm³. Processes used to make a fabric, such as weaving,fold the ePTFE fibers and may increase the density of the fibers whilepreserving breathability through the woven fabric. As a result, thefibers may have a post-weaving density less than or equal to about 1.2g/cm³. The low density of the fiber (both pre- and post-weave) alsoenhances the breathability of the fiber.

Additionally, the fibers may have a weight per length of about 50 dtexto about 3500 dtex, from about 70 dtex to about 1000 dtex, from about 80dtex to about 500 dtex, from about 90 dtex to about 400 dtex, from about100 dtex to about 300 dtex, or from about 100 dtex to about 200 dtex. Itis to be appreciated that a lower dtex provides a lower weight/areafabric, which enhances the comfort of a garment formed from the fabric.In addition, the low denier of the ePTFE fiber enables the woven fabricto have a high pick resistance. Pick resistance is referred to as theability of a fabric to resist the grasping and moving of individualfibers within the fabric. In general, the finer the fiber (e.g., lowerdenier or dtex) and tighter the weave, a better pick resistance isachieved.

The ePTFE fibers also have a height (thickness) (pre- or post-weaving)less than about 200 microns. In some embodiments, the thickness rangesfrom about 20 microns to about 150 microns, from 20 microns to about 100microns, from about 20 microns to about 70 microns, from about 20microns to 50 microns, from about 20 microns to 40 microns, or fromabout 26 microns to 36 microns. The ePTFE fibers may have a pre- orpost-weaving height (thickness) less than 100 microns, less than 75microns, less than 50 microns, less then 40 microns, less then 30microns, or less than 20 microns. The fibers also have a width (pre- orpost-weaving) less than about 4.0 mm. In at least one exemplaryembodiment, the fibers have a pre- or post-weaving width from about 0.5mm to about 4.0 mm, from about 0.40 mm to about 3.0 mm, from about 0.45mm to about 2.0 mm, or from about 0.45 mm to about 1.5 mm. The resultingaspect ratio (i.e., width to height ratio) of the ePTFE fibers isgreater than about 10. In some embodiments, the aspect ratio is greaterthan about 15, greater than about 20, greater than about 25, greaterthan about 30, greater than about 40, or greater than about 50. A highaspect ratio, such as is achieved by the ePTFE fibers, enables lowweight per area fabrics, easier and more efficient reshaping, and canachieve high water resistance in a woven fabric with less picks and endsper inch.

Further, the ePTFE fibers have a tenacity greater than about 1.4cN/dtex. In at least one embodiment of the invention, the ePTFE fibershave a tenacity from about 1.6 cN/dtex to about 5 cN/dtex, from about1.8 cN/dtex to about 4 cN/dtex, or from about 1.9 cN/dtex to about 3cN/dtex. Additionally, the ePTFE fibers have a fiber break strength ofat least about 1.5 N. In one or more embodiments, the ePTFE fibers havea fiber break strength from about 2 N to about 20 N, from about 2 N toabout 15 N, from about 2 N to about 10 N, or from about 2 N to about 5N.

The ePTFE fibers described herein may be used to form a woven fabrichaving warp and weft fibers interwoven with one another in a repeatingweave pattern. Any weave pattern, such as, but not limited to, plainweaves, satin weaves, twill weaves, and basket weaves, may be used toform the ePTFE fibers into a woven fabric. The ePTFE fiber may be wovenflat without folds or creases when the width of the ePTFE fiber is lessthan the allotted space provided for the fiber based on the number ofthe picks per inch and/or ends per inch. Such a fiber, when looselywoven, includes visible gaps between the crossovers (intersections) ofthe warp and weft fibers. As such, the fabric is highly breathable butis not water resistant. Such large gaps in the fabric may be acceptablein applications where, for example, the water resistance is to beprovided by another layer or in situations where general areal coverageis desired and water resistance is not critical.

In other embodiments, the fiber is more tightly woven, such as when thewidth of the ePTFE fiber exceeds the allotted space in the woven fabricbased on the number of picks per inch and/or ends per inch. In such afabric, there is no, or substantially no, gaps between the crossovers.The width of the ePTFE fiber may be greater than 1 times, greater thanabout 1.5 times, greater than about 2 times, greater than about 3 times,greater than about 4 times, greater than about 4.5 times, greater thanabout 5 times, greater than about 5.5 times, or greater than about 6times (or more) the space provided to the fibers based on the number ofpicks per inch and/or ends per inch. In other words, the ePTFE fibersare woven tighter than the width of the ePTFE fiber. In suchembodiments, the ePTFE fibers begin the weaving process in asubstantially rectangular configuration. However, due to the larger sizeof the fiber compared to the space provided by the picks per inch and/orends per inch, the ePTFE fibers curl and/or fold upon themselves toconform to the weave spacing determined by the number of picks per inchand/or ends per inch of the warp and weft fibers. Generally, the foldingor curling occurs in the width of the fiber such that the width of eachindividual fiber becomes smaller as the folding or curling of the fiberoccurs. The fibers are thus in a folded configuration along a length ofthe fiber.

The conformability of the ePTFE fibers is schematically depicted inFIGS. 40 and 41. In FIGS. 40 and 41, the fibers 10 are to be positionedin space (S) in a woven fabric. As shown in FIGS. 40 and 41, the widths(W) of the fibers 10 are larger than the space (S) allotted for thefibers 10 in the woven fabric. In order to fit into the space (S)allotted for the fibers 10, the fibers 10 fold or curl into a foldedconfiguration 15, such as is illustrated in FIG. 40.

The “foldability” or “folded configuration” of the ePTFE fibers isevidenced by a line 20 extending along the length of the fibers, as isshown in at least FIGS. 3, 5, 7, 10, 13, 16, 18, 20, 24, 26, 30, and 38.FIGS. 44 and 45, which are cross-section SEMs of an exemplary wovenfabric, illustrate the conformability of the ePTFE fibers, as thesefigures clearly depict the folding (and/or curling) of the fiber uponitself. FIG. 41 depicts a top schematic view of the fibers in a curledconfiguration. The fibers may fold upon themselves in the warp and/orthe weft direction. As shown in FIG. 41, the fibers conform to fit intospace (S). In a fabric including warp and weft fibers, at least one ofthe warp and weft fibers is in a folded configuration along, orsubstantially along, a length of the fiber. Thus, the ePTFE fibers foldand/or curl to a smaller width in the woven fabric. As one propheticexample, in a 88 ppi×88 epi woven fabric and an ePTFE fiber width of 1mm, the ePTFE fiber will fold upon itself to produce a folded width 3.5times less than its original width in order to accommodate the spaceprovided in the weave configuration (e.g. 88 ppi divided by 25.4 mm/1inch is 3.5 picks per mm).

The conformability of the ePTFE fiber allows larger sized ePTFE fibersto be utilized in smaller weave spacing. Increasing the number of picksper inch and/or ends per inch compared to the width of the fiber reducesor even eliminates gaps between where the warp and weft fibersintersect. Such tightly woven fabrics are concurrently highly breathableand water resistant (e.g., have a high water entry pressure). It is tobe appreciated that the fabric breathes not only through whatever gapmay be present but also through the ePTFE fiber itself. Even when thereare no gaps present, the woven fabric remains breathable. In contrast,conventional woven fabrics, when tightly woven, become non-breathable.

Not wishing to be bound by theory, it is believed that theconformability of the ePTFE fiber as well as the node and fibrilstructure enables the woven fabric to achieve many, if not all, of thefeatures and advantages described herein. For example, the nodes of theePTFE fiber help the fiber to maintain an “open” configuration of thefibrils when the fiber is woven. The open pores of the ePTFE fibersgreatly enhance the breathability of the woven fabric. The fineness ofthe pores prevents water into the fiber structure while maintaining highbreathability. As discussed previously, the conformability of the ePTFEfibers permits for the fibers to be woven in a tight configuration torender the woven fabric water resistant yet breathable.

Treatments may be provided to impart one or more desired functionality,such as, but not limited to, oleophobicity to the woven fabric. Whenprovided with an oleophobic coating, such as, but not limited to, afluoroacrylate olephobic coating, the woven fabric has an oil ratinggreater than or equal to 1, greater than or equal to 2, greater than orequal to 3, greater than or equal to 4, greater than or equal to 5, orgreater than or equal to 6 when tested according to the Oil Rating Testdescribed herein. Coatings or treatments, such as a fluoroacrylatecoating, may be applied to one or both sides of the woven fabric, andmay penetrate through or only partially through the woven fabric. It isto be understood that any functional protective layer, functionalcoating, or functional membrane, such as, but not limited to,polyamides, polyesters, polyurethanes, cellophane, non-fluoropolymermembranes that are both waterproof and breathable may be attached orotherwise affixed or layered on the woven fabric.

The woven fabric may be colored by a suitable colorant composition. TheePTFE fiber has a microstructure where the pores of the ePTFE fiber aresufficiently tight so as to provide water resistance and sufficientlyopen to provide properties such as moisture vapor transmission andpenetration by coatings of colorants. The ePTFE fiber has a surfacethat, when printed, provides a durable aesthetic. Aesthetic durabilitycan be achieved in some embodiments with colorant coating compositionsthat comprise a pigment having a particle size that is sufficientlysmall to fit within the pores of the ePTFE fiber and/or within the wovenfabric. Multiple colors may be applied using multiple pigments, byvarying the concentrations of one or more pigments, or by a combinationof these techniques. Additionally, the coating composition may beapplied in any form, such as a solid, pattern, or print. A coatingcomposition can be applied to the woven fabric by conventional printingmethods. Application methods for colorizing include but are not limitedto, transfer coating, screen printing, gravure printing, ink-jetprinting, and knife coating.

Unlike conventional woven fabrics, the ePTFE woven fabric is able tobreathe through the fibers forming the fabric (i.e., the ePTFE fibers)as well as through the gaps formed between the ePTFE fibers duringweaving. As discussed above, the ePTFE fibers have a node and fibrilconstruction that forms passageways through the fibers that make theePTFE fiber breathable. When the ePTFE fiber is woven, the node andfibril structure maintain open passageways. Thus, even when the ePTFEfiber is tightly woven such that there are no gaps or substantially nogaps formed in the woven structure, the ePTFE woven fabric maintains itshigh breathability. The ePTFE woven fabrics have a moisture vaportransmission rate (MVTR) that is greater than about 3000 g/m²/24 hours,greater than about 5000 g/m²/24 hours, greater than about 8000 g/m²/24hours, greater than about 10000 g/m²/24 hours, greater than about 12000g/m²/24 hours, greater than about 15000 g/m²/24 hours, greater thanabout 20000 g/m²/24 hours, or greater than about 25000 g/m²/24 hourswhen tested according to the moisture vapor transmission rate (MVTR)Test Method described herein. As used herein, the term “breathable” or“breathability” refers to woven fabrics or laminates that have amoisture vapor transmission rate (MVTR) of at least about 3000grams/m²/24 hours. Moisture vapor transmission, or breathability,provides cooling to a wearer of a garment, for example, made from thewoven fabric.

The woven fabrics also have an air permeability that is less than about500 cfm, less than about 300 cfm, less than 100 cfm, less than about 50cfm, less than about 25 cfm, less than about 20 cfm, less than about 15cfm, less than about 10 cfm, less than about 5 cfm, less than about 3cfm, and even less than about 2 cfm. It is to be understood that low airpermeability correlates to improved windproofness of the fabric.

ePTFE woven fabrics described herein have a water pick-up less than orequal to about 50 g/m², less than or equal to 40 g/m², less than orequal to about 30 g/m², less than or equal to about 25 g/m², less thanor equal to about 20 g/m², less than or equal to about 15 g/m², or lessthan or equal to about 10 g/m² and a water entry pressure of at leastabout 1 kPa, at least about 1.5 kPa, at least about 2 kPa, at leastabout 3 kPa, at least about 4 kPa, at least about 5 kPa, or at leastabout 6 kPa. The ePTFE fibers restrict the entry of water into the wovenfabric (into, e.g., the fiber structure and through the gaps of thewoven fabric), thus eliminating problems associated with conventionalwoven fabrics that absorb water, which, in turn, makes the fabricsheavier, and permits for thermal conductivity of the temperature of thewater through the fabric. Such thermal conductivity may be detrimentalin cases where the wearer is in a cold environment and the cold istransported to the body of the wearer.

Additionally, the woven fabrics are thin and lightweight, which permitsthe end user to easily carry and/or transport articles formed from thewoven fabrics. The woven fabrics may have a weight from about 50 g/m² toabout 500 g/m², from about 80 g/m² to about 300 g/m², or from about 90g/m² to about 250 g/m². Additionally, the woven fabrics may have aweight per unit area of less than about 1000 g/m², less than about 500g/m², less than about 400 g/m², less than about 300 g/m², less thanabout 200 g/m², less than about 150 g/m², or less than about 100 g/m².Further, the woven fabrics may have a height (thickness) from about 0.05mm to about 2 mm, from about 0.1 mm to about 1 mm, from about 0.1 mm toabout 0.6 mm, from about 0.1 mm to about 0.5 mm, from about 0.1 mm toabout 0.4 mm, from about 0.15 mm to about 0.25 mm, or from about 0.1 mmto about 0.3 mm. The thinness of the woven fabric enables articlesformed from the woven fabric to be folded compactly. The thin and lightweight features also contributes to the overall comfort of the wearer ofthe garment, especially during movement of the wearer as the wearerexperiences less restriction to movement.

Further, the woven fabrics have a soft hand and are drapable, makingthem suitable for use in garments, gloves, and footwear. The wovenfabric has an average stiffness less than about 1000 g, less than about500 g, less than about 400 g, less than about 300 g, less than about 250g, less than about 200 g, less than about 150 g, less than about 100 g,and even less than about 50 g. It was surprisingly discovered that inaddition to a soft hand, the woven fabrics demonstrated a reduction innoise associated with bending or folding the woven fabric. It wasfurther discovered that even with the addition of a porous polymermembrane, as discussed hereafter, the noise was reduced, particularlywhen compared to conventional ePTFE laminates.

The woven fabrics are also resistant to tearing. For example, the wovenfabric has a tear strength from about 10 N to about 200 N (or evengreater), from about 15 N to about 150 N, or from about 20 N to about100 N as measured by the Elemendorf Tear test described herein. Such ahigh tear strength enables the woven fabric to be more durable in use.

In at least one embodiment, a porous or microporous polymer membrane islaminated or bonded to the woven fabric. Non-limiting examples of porousmembranes including expanded PTFE, expanded modified PTFE, expandedcopolymers of PTFE, fluorinated ethylene propylene (FEP), andperfluoroalkoxy copolymer resin (PFA). Polymeric materials such aspolyolefins (e.g., polypropylene and polyethylene), polyurethanes, andpolyesters are considered to be within the purview of the inventionprovided that the polymeric material can be processed to form porous ormicroporous membrane structures. It is to be appreciated that even whenthe inventive woven fabric is laminated or bonded to a porous ormicroporous membrane, the resulting laminate remains highly breathableand substantially maintains the breathability of the woven fabric. Inother words, the porous or microporous membrane laminated to the wovenfabric does not affect, or only minimally affects, the breathability ofthe woven fabric, even when laminated.

The microporous membrane may be an asymmetric membrane. As used herein,“asymmetric” is meant to indicate that the membrane structure includesmultiple layers of ePTFE within the membrane where at least one layerwithin the membrane has a microstructure that is different from themicrostructure of a second layer within the membrane. The differencebetween the first microstructure and the second microstructure may becaused by, for example, a difference in pore size, a difference in nodeand/or fibril geometry or size, and/or a difference in density.

In a further embodiment, a textile may be attached to the microporousmembrane or directly to the woven fabric. As used herein, the term“textile” is meant to denote any woven, nonwoven, felt, fleece, or knitand can be composed of natural and/or synthetic fiber materials and/orother fibers or flocking materials. For example, the textile may becomprised of materials such as, but not limited to cotton, rayon, nylon,polyester, and blends thereof. The weight of the material forming thetextile is not particularly limited except as required by theapplication. In exemplary embodiments, the textile is air permeable andbreathable.

Any suitable process for joining the membrane and/or the textile to thewoven fabric (and textile to the membrane) may be used, such as gravurelamination, fusion bonding, spray adhesive bonding, and the like. Theadhesive may be applied discontinuously or continuously, provided thatbreathability through the laminate is maintained. For example, theadhesive may be applied in the form of discontinuous attachments, suchas by discrete dots or grid pattern, or in the form of an adhesive webto adhere layers of the laminate together.

The ePTFE woven fabric is suitable for use in various applications,including but not limited to garments, tents, covers, bivy bags,footwear, gloves, and the like. The woven fabric is concurrently highlybreathable and water resistant. These advantageous features areachieved, at least in part, due to the high aspect ratio of the ePTFEfiber. The ePTFE woven fabric can be used alone, or it can be used inconjunction with a fluoropolymer membrane and/or textile. The surface ofthe ePTFE woven fabric can be colorized, for example, by printing.Additionally, the surface of the ePTFE fabric and/or the ePTFE fiber canbe coated with an oleophobic coating composition to provideoleophobicity. It should be appreciated that the benefits and advantagesdescribed herein equally apply to knitted fabrics and articles as wellas the woven fabrics and articles discussed herein.

TEST METHODS

It should be understood that although certain methods and equipment aredescribed below, any method or equipment determined suitable by one ofordinary skill in the art may be alternatively utilized.

Fiber Weight per Length

A 45 meter length of fiber was obtained using a skein reel. The 45 meterlength was then weighed on a scale with precision to 0.0001 grams. Thisweight was then multiplied by 200 to give the weight per length in termsof denier (g/9000 m). This value was then multiplied by 10 and dividedby 9 to give the weight per length in terms of dtex (g/10,000 m).

Fiber Width

Fiber width was measured in a conventional manner utilizing a 10× eyeloop having gradations to the nearest 0.1 mm. Three measurements weretaken and averaged to determine the width to the nearest 0.05 mm.

Fiber Thickness

Fiber thickness was measured utilizing a snap gauge accurate to thenearest 0.0001 inch. Care was taken to not to compress the fibers withthe snap gauge. Three measurements were taken and averaged and thenconverted to the nearest 0.0001 mm.

Fiber Density

Fiber density was calculated utilizing the previously measured fiberweight per length, fiber width and fiber thickness using the followingformula:

${{Fiber}\mspace{14mu} {Density}\mspace{14mu} \left( {g\text{/}{cm}^{3}} \right)} = \frac{{Fiber}\mspace{14mu} {wt}\mspace{14mu} {per}\mspace{14mu} {length}\mspace{14mu} ({dtex})}{{{Fiber}\mspace{14mu} {Width}\mspace{14mu} ({mm})*{Fiber}\mspace{14mu} {Thickness}\mspace{14mu} ({mm})*10},000}$

Fiber Break Strength

The fiber break strength was the measurement of the maximum load neededto break (rupture) the fiber. The break strength was measured by atensile tester, such as an Instron® Machine of Canton, Mass. TheInstron® machine was outfitted with fiber (horn type) jaws that aresuitable for securing fibers and strand goods during the measurement oftensile loading. The cross-head speed of the tensile tester was 25.4 cmper minute. The gauge length was 25.4 cm. Five measurements of eachfiber type were taken with the average reported in units of Newtons.

Fiber Tenacity

Fiber tenacity is the break strength of the fiber normalized to theweight per length of the fiber. Fiber tenacity was calculated using thefollowing formula:

${{Fiber}\mspace{14mu} {tenacity}\mspace{14mu} \left( {{cN}\text{/}{dtex}} \right)} = \frac{{Fiber}\mspace{14mu} {break}\mspace{14mu} {strength}\mspace{14mu} (N)*100}{{Fiber}\mspace{14mu} {weight}\mspace{14mu} {per}\mspace{14mu} {length}\mspace{14mu} ({dtex})}$

Fabric and Membrane Thickness

The fabric and membrane thicknesses were measured by placing either themembrane or textile laminate between the two plates of a Mitutoyo543-252BS Snap Gauge. The average of the three measurements was used. Itis to be appreciated that the thickness of the fabric and/or themembrane may be determined by any suitable method as determined by oneof skill in the art.

Matrix Tensile Strength (MTS) of Membrane

Matrix Tensile Strength of the membrane was measured using an Instron®1122 tensile test machine equipped with flat-faced grips and a 0.445 kNload cell. The gauge length was 5.08 cm and the cross-head speed was50.8 cm/min. The sample dimensions were 2.54 cm by 15.24 cm. To ensurecomparable results, the laboratory temperature was maintained between68° F. (20° C.) and 72° F. (22.2° C.) to ensure comparable results. Datawas discarded if the sample broke at the grip interface.

For longitudinal MTS measurements, the larger dimension of the samplewas oriented in the machine, or “down web,” direction. For thetransverse MTS measurements, the larger dimension of the sample wasoriented perpendicular to the machine direction, also known as the“cross web” direction. Each sample was weighed using a Mettler ToledoScale Model AG204. The thickness of the samples was then measured usinga Kafer FZ1000/30 snap gauge. The samples were then tested individuallyon the tensile tester. Three different sections of each sample weremeasured. The average of the three maximum load (i.e., the peak force)measurements was used.

The longitudinal and transverse MTS were calculated using the followingequation:

MTS=(maximum load/cross-section area)*(bulk density of PTFE)/density ofthe porous membrane),

where the bulk density of PTFE is taken to be 2.2 g/cm³.

The average of three cross-web measurements was recorded as thelongitudinal and transverse MTS.

Density of Membrane

To calculate the density of the membrane, measurements from the

Matrix Tensile Testing were used. As mentioned above, the sampledimensions were 2.54 cm by 15.24 cm. Each sample was weighed using aMettler Toledo Scale Model AG204 and then the thickness of the sampleswas taken using a Kafer FZ1000/30 snap gauge. Using this data, a densityof the sample can be calculated with the following formula:

$\rho = \frac{m}{w*l*t}$

where:

-   -   ρ=density (g/cm³)    -   m=mass (g)    -   w=width (1.5 cm)    -   l=length (16.5 cm)    -   t=thickness (cm)

The reported results are the average of three calculations.

Gurley Air Flow of Membrane

The Gurley air flow test measures the time in seconds for 100 cm³ of airto flow through a 6.45 cm² sample at 12.4 cm of water pressure. Thesamples were measured in a Gurley Densometer Model 4340 AutomaticDensometer. When multiple tests are performed on the same sample, caremust be taken to ensure that the edges of the test areas do not overlap.(The compression that occurs to the material along the edges of the testarea when it is clamped to create a seal during a Gurley test can affectthe air flow results.) The reported results are the average of threemeasurements.

Moisture Vapor Transmission Rate Test—(MVTR)

The MVTR for each sample fabric was determined in accordance with thegeneral teachings of ISO 15496 except that the sample water vaportransmission (WVP) was converted into MVTR moisture vapor transmissionrate (MVTR) based on the apparatus water vapor transmission (WVPapp) andusing the following conversion.

MVTR=(Delta P value*24)/((1/WVP)+(1+WVPapp value))

To ensure comparable results, the specimens were conditioned at73.4±0.4° F. and 50±2% rH for 2 hrs prior to testing and the bath waterwas a constant 73.4° F.±0.4° F.

The MVTR for each sample was measured once, and the results are reportedas g/m²/24 hours.

Mass/Area

In order to measure mass per area, fabric samples were prepared havingan area of at least 100 cm². A Karl Schroder 100 cm² circle cutter maybe used. Each sample was weighed using a Mettler Toledo Scale ModelAB204. The scale was recalibrated prior to weighing specimens, and theresults were reported in grams per square meter (gsm). For membranesamples, the reported results are the average of three measurements. Forprinted laminate samples, the reported data is the result of a singlemeasurement.

Oil Rating Test

Oil rating of both membranes and laminates were measured. Tests wereconducted following the general teachings of AATCC Test Method 118-1997.The oil rating number is the highest number oil which does not wet thematerial within a test exposure time of 30±2 seconds. The reportedresults are the average of three measurements.

SEM Sample Preparation Method

Cross-section SEM samples were prepared by spraying them with liquidnitrogen and then cutting the sprayed samples with a diamond knife in aLeica ultracut UCT, available from Leica Microsystems, Wetzlar, Germany.

Fibril Length Measurement

The surface SEM images were used to measure fibril length. Amagnification was chosen to enable the viewing of multiple fibrils,including a clear view of the points where fibrils attached to nodes.The same magnification was used for each sample that was measured. Sincethese node and fibril structures were irregular, 15 different fibrils,randomly distributed across each image, were identified for measurement.

To measure each fibril accurately, lines were drawn with the cursor sothat they were perpendicular to the fibril on both ends where the fibrilattaches to the node. The distance between the cursor drawn lines weremeasured, and recorded for each fibril. The results for each surfaceimage of each sample were averaged. The reported value for fibril lengthrepresents the average of 15 sample measurements on the SEM image.

Liquidproof Test (Suter) and Water Pick-Up

Liquidproof testing and water pick-up was conducted as follows.Laminates were tested for liquidproofness by using a modified Suter testapparatus with water serving as a representative test liquid. Water isforced against a sample area of about 4¼ A inch (10.8 cm) diametersealed by two rubber gaskets in a clamped arrangement. Samples aretested by orienting the sample so that the outer film surface of thesample is the surface against which water is forced. The water pressureon the sample is increased to about 0.7 psi (6.94.81 KPa) by a pumpconnected to a water reservoir, as indicated by an appropriate gauge andregulated by an in-line valve. The test sample was positioned at anangle, and the water was recirculated to ensure that water, not air,contacted the lower surface of the sample. The surface opposite theouter film surface of the sample was observed for a period of 3 minutesfor the appearance of any water which would be forced through thesample. Liquid water seen on the surface was interpreted as a leak.

A passing (liquidproof) grade was given in cases where no liquid wateris visible on the sample surface within 3 minutes. A sample was deemed“liquidproof” as used herein if it passed this test. Samples having anyvisible liquid water leakage, e.g. in the form of weeping, pin holeleak, etc. were not considered liquidproof and failed the test.

To determine water pick up the sample was weighed before and after thetest. The difference in grams was converted to grams per square meterfrom a 10.8 cm diameter circle sample, thereby providing the weightincrease picked up from water. The reported results are the average ofthree measurements.

Gap Between Fibers Measurement

Surface SEM images were used to measure the gap between fibers. Amagnification was chosen to enable the viewing of at least ten fibercrossovers, including a clear view of the gaps where the fibers overlap.For each gap, the distance (D) between the fibers, at the crossovers 30as shown in FIG. 52, was measured to the nearest micrometer in the warpdirection. This distance (D) was measured and averaged for at least tencrossovers within the field of view. It is to be noted that only twocrossovers 30 are depicted in FIG. 52, and are for purposes ofillustration only. Also, for each gap, the distance (D′) orthogonal tothe direction corresponding to distance between the fibers at thecrossovers 30 was measured to the nearest micrometer in the filldirection. This distance D′ was measured and averaged for at least tencrossovers within the field of view. The average gap distance (D) in thewarp direction and the average gap distance (D′) in the fill directionwere reported, with the larger value reported first.

Water Entry Pressure (WEP)

Water entry pressure provides a test method for water intrusion throughmembranes and/or fabrics. A test sample is clamped between a pair oftesting plates. The lower plate has the ability to pressurize a sectionof the sample with water. A piece of pH paper is placed on top of thesample between the plate on the non-pressurized side as an indicator ofevidence for water entry. The sample is then pressurized in smallincrements, waiting 10 seconds after each pressure change until a colorchange in the pH paper indicates the first sign of water entry. Thewater pressure at breakthrough or entry is recorded as the Water EntryPressure. The test results are taken from the center of test sample toavoid erroneous results that may occur from damaged edges.

Tear Strength

This test is designed to determine the average force required topropagate a single-rip tongue-type tear starting from a cut in wovenfabric. A Thwing-Albert Heavy Duty Elmendorf Tearing Tester (MAI227) wasused. After the instrument was calibrated and the correct pendulumweight was selected, a blinking asterisk on the left side of the displaywill indicate the instrument is ready for testing. The pendulum wasraised to the starting position. The specimen was placed in jaws andclamped using the air clamp located on the lower right side ofinstrument. The air pressure was between 414 KPa and 621 KPa. Thespecimen was centered with the bottom edge carefully against the stops.The upper area of the specimen should be directed towards the pendulumto ensure a shearing action. The test was performed until a completetear was achieved. The digital readout was recorded in Newtons. This wasrepeated until a set (1 warp and 1 weft). The reported results are theaverage of the measurements for one set.

Stiffness

A Thwing Albert Handle-O-Meter with a 1000 g beam and ¼″ slot width wasused to measure the hand (stiffness). A 4″×4″ sample was cut from thefabric. The specimen was placed face up on the specimen platform. Thespecimen was lined up so that the test direction is perpendicular to theslot to test the warp direction. The START/Test button was pressed untila click is heard, then released. The number appearing on the digitaldisplay after a second click is heard was recorded. The reading will notreturn to zero but will show the peak reading of each individual test.The specimen was turned over and tested again, recording the number.Then the specimen was turned 90 degrees to test the fill direction,recording the number. Finally, the specimen was turned over and testedagain, recording the number. The 4 recorded numbers were added together(1 Warp Face, 1 Warp Back, 1 Fill face, 1 Fill Back) to calculate theoverall stiffness of the specimen in grams. The results were reportedfor one sample.

Air Permeability—Frazier Number Method

Air permeability was measured by clamping a test sample in a gasketedflanged fixture which provided a circular area of approximately 6 squareinches (2.75 inches diameter) for air flow measurement. The upstreamside of the sample fixture was connected to a flow meter in line with asource of dry compressed air. The downstream side of the sample fixturewas open to the atmosphere.

Testing was accomplished by applying a pressure of 0.5 inches of waterto the upstream side of the sample and recording the flow rate of theair passing through the in-line flowmeter (a ball-float rotameter).

The sample was conditioned at 70° F. (21.1° C.) and 65% relativehumidity for at least 4 hours prior to testing.

Results are reported in terms of Frazier Number which is air flow incubic feet/minute/square foot of sample at 0.5 inches water pressure.

EXAMPLES Example 1a

A fine powder PTFE resin (Teflon 669 X, commercially available from E.I.du Pont de Nemours, Inc., Wilmington, Del.) was obtained. The resin wasblended with Isopar® K in the ratio of 0.184 g/g by weight of powder.The lubricated powder was compressed in a cylinder and allowed to dwellat room temperature for 18 hours. The pellet was then ram extruded at a169 to one reduction ratio to produce a tape of approximately 0.64 mmthick. The extruded tape was subsequently compressed to a thickness of0.25 mm. The compressed tape was then stretched in the longitudinaldirection between two banks of rolls. The speed ratio between the secondbank of rolls and the first bank of rolls, hence the stretch ratio was1.4:1 with a stretch rate of 30%/sec. The stretched tape was thenrestrained and dried at 200° C. The dry tape was then expanded betweenbanks of heated rolls in a heated chamber at a temperature of 300° C. toa ratio of 1.02:1 at a stretch rate of 0.2%/sec, followed by anadditional expansion ratio of 1.75:1 at a stretch rate of 46%/sec,followed by an additional expansion ratio of 1.02:1 at a stretch rate of0.5%/sec. This process produced a tape with a thickness of 0.24 mm.

This tape was then slit to create a cross-section of 1.78 mm wide by0.24 mm thick and having a weight per length of 3494 dtex. The slit tapewas then expanded over a heated plate set to 390° C. at a stretch ratioof 6.25:1 with a stretch rate of 65%/sec. This was followed by furtherexpansion across a heated plate set to 390° C. at a stretch ratio of2.50:1 with a stretch rate of 66%/sec. This was followed by a furtherexpansion across a heated plate set to 390° C. at a stretch ratio of1.30:1 with a stretch rate of 23%/sec. This was followed by runningacross a heated plate set to 390° C. at a stretch ratio of 1.00:1 for aduration of 1.6 seconds, resulting in an amorphously locked expandedPTFE fiber.

The final amorphously locked ePTFE fiber measured 172 dtex and had arectangular cross-section and possessed the following properties:width=1.0 mm, height=0.0356 mm, density=0.48 g/cm³, break strength of3.51 N, tenacity of 2.04 cN/dtex, and fibril length=53.7 microns.

A scanning electron micrograph (SEM) of a side of the resulting fibertaken at 1000× magnification is shown in FIG. 1. FIG. 2 is a scanningelectron micrograph of the top surface of the fiber taken at 1000×magnification.

The fiber was then used to create a woven fabric. The weaving patternwas 2/2 twill using a thread count of 88×88 threads/inch. The wovenfabric had the following properties: thickness=0.20 mm, MVTR=27860g/m²/24 hours, water pick-up=13 gsm, hand=71 g, tear strength=75.6 N,WEP=5.38 kPa, air permeability=0.81 cfm, and oil rating=<1. A scanningelectron micrograph of the surface of the fabric taken at 150×magnification is depicted in FIG. 3. A scanning electron micrograph of aside view of the fabric taken at 150× magnification is shown in FIG. 4.The length and width of the gaps between the warp and weft fibers wereless than 0.01 mm. The fabric had a weight of 135 g/m².

A fiber (172 dtex) was removed from the woven fabric and dimensionalmeasurements were taken of its conformed state post-weaving in order todemonstrate the conformability of the fiber. The fiber was determined tohave a post-weaving folded width of 0.30 mm, a post-weaving foldedheight of 0.0699 mm, a post-weaving aspect ratio of 4.3, and apost-weaving density of 0.82 g/cm³. The pre-woven width to thepost-weaving folded width ratio was 3.3 to 1.

Example 1b

A fluoroacrylate coating was applied to the woven fabric of Example 1ain order to render it oleophobic while preserving the porous andmicroporous structure.

The resulting oleophobic woven fabric had the following properties:thickness=0.20 mm, MVTR=21206 g/m²/24 hours, water pick-up=11 gsm,hand=131 g, tear strength=63.8 N, WEP=6.11 KPa, air permeability=1.72cfm, and oil rating=6. A scanning electron micrograph of surface of thewoven fabric taken at 150× magnification is shown in FIG. 5. A scanningelectron micrograph of a side view of the fabric taken at 150×magnification is shown in FIG. 6. The length and width of the gapsbetween the fibers were less than 0.01 mm. The fabric had a weight of158 g/m².

Example 1c

An amorphously locked ePTFE membrane was obtained having the followingproperties: thickness=0.04 mm, density=0.47 g/cc, matrix tensilestrength in the strongest direction=105.8 MPa, matrix tensile strengthin the direction orthogonal to the strongest direction=49.9 MPa,Gurley=16.2 s, MVTR=64168 g/m²/24 hours.

The woven fabric of Example 1b was laminated to the ePTFE membrane inthe following manner. The fabric and the ePTFE membrane were bondedtogether by applying a dot pattern of a melted polyurethane adhesive tothe membrane. While the polyurethane adhesive dots were molten, thefabric was positioned on top of the adhesive side of the membrane. Thisconstruct (article) was allowed to cool.

The resulting article had the following properties: thickness=0.22 mm,MVTR=12845 g/m²/24 hours, water pick-up=12 gsm, hand=196 g, tearstrength=46.19 N, and oil rating=6. A scanning electron micrograph ofthe top surface of the article taken at 150× magnification is presentedin FIG. 7. A side view of the article taken at 100× magnification isshown in FIG. 8. A side view of the article taken at 1000× magnificationis shown in FIG. 9. The length and width of the gaps between the fiberswere less than 0.01 mm. The fabric had a weight of 192 g/m².

Example 1d

The woven fabric of Example 1b was laminated to a plain weave nylontextile (weight of 18 g/m², 150 ends per inch, and 109 picks per inch,17 dtex (5 filaments) in the following manner. The fabric and thetextile were bonded together by applying a dot pattern of a meltedpolyurethane adhesive to the fabric. While the polyurethane adhesivedots were molten, the textile was positioned on top of the adhesive sideof the fabric. This construct was allowed to cool.

The resulting article had the following properties: thickness=0.25 mm,MVTR=14407 g/m²/24 hours, water pick-up=54 gsm, hand=288 g, tearstrength=43.18 N, WEP=5.72; KPa, air permeability=0.86 cfm, and oilrating=6. A scanning electron micrograph of the top surface of thearticle taken at 150× magnification is presented in FIG. 10. A scanningelectron micrograph of a side view of the article taken at 100×magnification is shown in FIG. 11. A scanning electron micrograph of aside view of the article taken at 500× magnification is shown in FIG.12. The length and width of the gaps between the fibers were less than0.01 mm. The fabric had a weight of 192 g/m².

Example 1e

A laminated article was constructed in the following manner. Themembrane and the textile as described in Example 1a were bonded togetherby applying a dot pattern of a melted polyurethane adhesive to themembrane. While the polyurethane adhesive dots were molten, the textilewas positioned on top of the adhesive side of the fabric. This constructwas allowed to cool. Next, the fabric was bonded to the membrane byapplying a dot pattern of a melted polyurethane adhesive to themembrane. While the polyurethane adhesive dots were molten, the fabricwas positioned on top of the membrane. This construct was allowed tocool.

The resulting article had the following properties: thickness=0.26 mm,MVTR=8708 g/m²/24 hours, water pick-up=11 gsm, hand=526 g, tearstrength=37.78 N, and oil rating=6. A scanning electron micrograph ofthe top surface of the article taken at 150× magnification is shown inFIG. 13. A scanning electron micrograph of a side view of the articletaken at 100× magnification is shown in FIG. 14. A scanning electronmicrograph of a side view of the article taken at 300× magnification isshown in FIG. 15. The length and width of the gaps between the fiberswere less than 0.01 mm. The fabric had a weight of 216 g/m².

Example 2a

A woven fabric was constructed in the same manner as described inExample 1a with the exception that the weave pattern was a plain weave.The woven fabric had the following properties: thickness=0.15 mm,MVTR=21336 g/m²/24 hours, water pick-up=4 gsm, hand=83 g, oil rating=<1,WEP=3.13 KPa, air permeability=0.44 cfm, and tear strength=36.3 N. Ascanning electron micrograph of the top surface of the fabric taken at150× magnification is shown in FIG. 16. A scanning electron micrographof a side view of the article taken at 250× magnification is shown inFIG. 17. The length and width of the gaps between the fibers were about0.01 mm and 0.01 mm, respectively. The fabric had a weight of 142 g/m².

A fiber (172 dtex) was removed from the woven fabric and dimensionalmeasurements were taken of its conformed state post-weaving in order todemonstrate the conformability of the fiber. The fiber was determined tohave a post-weaving folded width of 0.25 mm, a post-weaving foldedheight of 0.0736 mm, a post-weaving aspect ratio of 3.4, and apost-weaving density of 0.94 g/cm³. The pre-woven width to thepost-weaving folded width ratio was 4.0 to 1.

Example 2b

The woven fabric of Example 2a was rendered oleophobic in the samemanner as described in Example 1b.

The oleophobic woven fabric had the following properties: thickness=0.16mm, MVTR=13265 g/m²/24 hours, water pick-up=7 gsm, hand=141 g, tearstrength=30.3 N, WEP=4.01 KPa, Air permeability=0.49 cfm, and oilrating=6. A scanning electron micrograph of the top surface of thefabric taken at 150× magnification is presented in FIG. 18. A scanningelectron micrograph of a side view of the fabric taken at 250×magnification is shown in FIG. 19. The length and width of the gapsbetween the fibers were about 0.01 mm and 0.02 mm, respectively. Thefabric had a weight of 158 g/m².

Example 2c

An oleophobic laminated article was constructed in the following manner.The membrane and the textile were bonded together by applying a dotpattern of a melted polyurethane adhesive to the membrane. While thepolyurethane adhesive dots were molten, the textile was positioned ontop of the adhesive side of the fabric. This construct was allowed tocool. Next, the fabric was bonded to the membrane by applying a dotpattern of a melted polyurethane adhesive to the membrane. While thepolyurethane adhesive dots were molten, the fabric was positioned on topof the membrane. This construct was allowed to cool.

The resulting article had the following properties: thickness=0.24 mm,MVTR=8274 g/m²/24 hours, water pick-up=10 gsm, hand=465 g, tearstrength=20.59 N, and oil rating=6. A scanning electron micrograph ofthe top surface of the article taken at 150× magnification is presentedin FIG. 20. A scanning electron micrograph of a side view of the articletaken at 250× magnification is shown in FIG. 21. The length and width ofthe gaps between the fibers were about 0.01 mm and 0.03 mm,respectively. The fabric had a weight of 214 g/m².

Example 3a

A tape was produced in the same manner as described in Example 1a. Thistape was then slit to create a cross-section of 1.14 mm wide by 0.24 mmthick and having a weight per length of 2184 dtex. The slit tape wasthen expanded across a heated plate set to 390° C. at a stretch ratio of6.00:1 with a stretch rate of 70%/sec. This was followed by expansionacross a heated plate set to 390° C. at a stretch ratio of 2.50:1 with astretch rate of 74%/sec. This was followed by a further expansion acrossa heated plate set to 390° C. at a stretch ratio of 1.30:1 with astretch rate of 26%/sec. This was followed by running across a heatedplate set to 390° C. at a stretch ratio of 1.00:1 for a duration of 1.4seconds resulting in an amorphously locked expanded PTFE fiber.

The amorphously locked ePTFE fiber measured 112 dtex and had arectangular cross-section and possessed the following properties:width=0.7 mm, height=0.0356 mm, density=0.45 g/cm3, break strength of2.14 N, tenacity of 1.92 cN/dtex, and fibril length=57.2 microns.

A scanning electron micrograph of the fiber taken at 1000× magnificationis shown in FIG. 22. A scanning electron micrograph of a side view ofthe fiber taken at 1000× magnification is shown in FIG. 23.

The fiber was used to create a woven fabric. The weaving pattern was 2/2twill and a thread count of 100×100 threads/inch. The woven fabric hadthe following properties: thickness=0.15 mm, MVTR=32012 g/m²/24 hours,water pick-up=21 gsm, hand=47 g, oil rating=<1, WEP=2.15 KPa, airpermeability=1.17 cfm, and tear strength=57.8 N. A scanning electronmicrograph of the woven fabric taken at 150× magnification is shown inFIG. 24. A scanning electron micrograph of a side view of the fabrictaken at 200× magnification is shown in FIG. 25. The length and width ofthe gaps between the fibers were less than 0.01 mm. The fabric had aweight of 102 g/m².

A fiber (112 dtex) was removed from the woven fabric and dimensionalmeasurements were taken of its conformed state post-weaving in order todemonstrate the conformability of the fiber. The fiber had apost-weaving folded width of 0.25 mm, a post-weaving folded height of0.0559 mm, a post-weaving aspect ratio of 4.5, and a post-weavingdensity of 0.80 g/cm³. The pre-woven width to the post-weaving foldedwidth ratio was 2.8 to 1.

Example 3b

The woven fabric of Example 3a was rendered oleophobic in the samemanner as described in Example 1b. This article had the followingproperties: thickness=0.15 mm, MVTR=20526 g/m²/24 hours, waterpick-up=15 gsm, hand=86 g, tear strength=48.2 N, WEP=5.45 KPa, airpermeability=1.85 cfm, and oil rating=6. A scanning electron micrographof the fabric taken at 150× magnification is shown in FIG. 26. Ascanning electron micrograph of a side view of the fabric taken at 200×magnification is shown in FIG. 27. The length and width of the gapsbetween the fibers were less than 0.01 mm. The fabric had a weight of120 g/m².

Example 4

A fine powder PTFE resin (Teflon 669 X, commercially available from E.I.du Pont de Nemours, Inc., Wilmington, Del.) was obtained. The resin wasblended with Isopar® K in the ratio of 0.184 g/g by weight of powder.The lubricated powder was compressed in a cylinder and placed in an ovenat a temperature of 49° C. for 18 hours. The pellet was then ramextruded at a 169 to one reduction ratio to produce a tape ofapproximately 0.64 mm thick. The extruded tape was subsequentlycompressed to a thickness of 0.25 mm. The compressed tape was thenstretched in the longitudinal direction between two banks of rolls. Thespeed ratio between the second bank of rolls and the first bank ofrolls, hence the stretch ratio was 1.4:1 with a stretch rate of 30%/sec.The stretched tape was then restrained and dried at 200° C. The dry tapewas then expanded between banks of heated rolls in a heated chamber at atemperature of 300° C. to a ratio of 1.02:1 at a stretch rate of0.2%/sec, followed by an additional expansion ratio of 1.75:1 at astretch rate of 46%/sec, followed by an additional expansion ratio of1.02:1 at a stretch rate of 0.5%/sec. This process produced a tape witha thickness of 0.24 mm thick.

This tape was then slit to create a cross-section of 1.14 mm wide by0.24 mm thick and having a weight per length of 2373 dtex. The slit tapewas then expanded across a heated plate set to 390° C. at a stretchratio of 6.00:1 with a stretch rate of 69%/sec. This was followed byfurther expansion across a heated plate set to 390° C. at a stretchratio of 2.20:1 with a stretch rate of 32%/sec. This was followed by afurther expansion across a heated plate set to 390° C. at a stretchratio of 1.40:1 with a stretch rate of 19%/sec. This was followed by afurther expansion across a heated plate set to 390° C. at a stretchratio of 1.20:1 with a stretch rate of 12%/sec. This was followed byrunning across a heated plate set to 390° C. at a stretch ratio of1.00:1 for a duration of 2.1 seconds, resulting in an amorphously lockedexpanded PTFE fiber.

The final amorphously locked ePTFE fiber measured 107 dtex and had arectangular cross-section and possessed the following properties:width=0.45 mm, height=0.0279 mm, density=0.85 g/cm³, break strength of3.20 N, tenacity of 3.01 cN/dtex, and fibril length=16.1 microns.

A scanning electron micrograph of the top surface of the fiber taken at1000× magnification is shown in FIG. 28. FIG. 29 is a scanning electronmicrograph of a side view of the fiber taken at 1000× magnification.

The fiber was used to create a woven fabric. The weaving pattern was 2/2twill and a thread count of 100×100 threads/inch. The woven fabric hadthe following properties: thickness=0.13 mm, MVTR=28497 g/m²/24 hours,water pick-up=5 gsm, hand=72 g, oil rating=<1, WEP=1.96 KPa, Airpermeability=2.4 cfm, and tear strength=71.2 N. A scanning electronmicrograph of the top surface of the fabric taken at 150× magnificationis shown in FIG. 30. A side view of the fabric taken at 150×magnification is shown in FIG. 31. The length and width of the gapsbetween the fibers were less than 0.01 mm. The fabric had a weight of 93g/m².

A fiber (107 dtex) was removed from the woven fabric and dimensionalmeasurements were taken of its conformed state post-weaving in order todemonstrate the conformability of the fiber. The fiber had apost-weaving folded width of 0.25 mm, a post-weaving folded height of0.0356 mm, a post-weaving aspect ratio of 7.0, and a post-weavingdensity of 1.20 g/cm³. The pre-woven width to the post-weaving foldedwidth ratio was 1.8 to 1.

Example 5

A tape was produced in the same way as in Example 1a. This tape was thenslit to create a cross-section of 4.57 mm wide by 0.236 mm thick andhaving a weight per length of 7937 dtex. The slit tape was then expandedacross a heated plate set to 390° C. at a stretch ratio of 6.00:1 with astretch rate of 70%/sec. This was followed by another expansion across aheated plate set to 390° C. at a stretch ratio of 2.50:1 with a stretchrate of 74%/sec. This was followed by a further expansion across aheated plate set to 390° C. at a stretch ratio of 1.30:1 with a stretchrate of 26%/sec. This was followed by running across a heated plate setto 390° C. at a stretch ratio of 1.00:1 for a duration of 1.4 seconds,resulting in an amorphously locked expanded PTFE fiber.

The amorphously locked ePTFE fiber measured 452 dtex and had arectangular cross-section and possessed the following properties:width=2.2 mm, height=0.0406 mm, density=0.51 g/cm3, break strength of11.48 N, tenacity of 2.55 cN/dtex, and fibril length=60 microns. Ascanning electron micrograph of the fiber surface taken at 1000×magnification is shown in FIG. 36. A scanning electron micrograph of aside view of the fiber taken at 1000× magnification is shown in FIG. 37.

The weaving pattern was a plain weave and had a thread count of 50×50threads/inch (19.7×19.7 threads/cm). The ratio of the pre-woven fiberwidth to the calculated allotted space per fiber within the weavepattern was 4.3 to 1. The woven fabric had the following properties:thickness=0.24 mm, MVTR=14798 g/m²/24 hours, water pick-up=15 gsm,hand=281 g, oil rating=<1, WEP=1.86 kPa, air permeability=2.1 cfm. Ascanning electron micrograph of the woven fabric taken at 150×magnification is shown in FIG. 38. A scanning electron micrograph of aside view of the fabric taken at 150× magnification is shown in FIG. 39.The length and width of the gaps between the fibers were about 0.04 mmand 0.01 mm, respectively. Scanning electron micrographs of the topsurface of the fabric taken at 120× magnification depicting the gapwidth measurements in the horizontal direction and the gap widthmeasurements in the vertical direction are shown in FIGS. 40 and 41,respectively. The fabric had a weight of 211 g/m².

A fiber (452 dtex) was removed from the woven fabric and dimensionalmeasurements were taken of its conformed state post-weaving in order todemonstrate the conformability of the fiber. The fiber had apost-weaving folded width of 0.40 mm, a post-weaving folded height of0.1524 mm, a post-weaving aspect ratio of 2.6, and a post-weavingdensity of 0.74 g/cm³. The pre-woven width to the post-weaving foldedwidth ratio was 5.5 to 1.

Example 6

A woven fabric was constructed in the same manner as described inExample 5 with the exception that the plain weave pattern had a threadcount of 40×40 threads/inch (15.7×15.7 threads/cm). The woven fabric hadthe following properties: thickness=0.25 mm, MVTR=27846 g/m²/24 hours,water pick-up=7 gsm, hand=71 g, oil rating=<1, WEP=1.69 KPa, and airpermeability=3.87 cfm. A scanning electron micrograph of the top surfaceof the fabric taken at 150× magnification is shown in FIG. 42. Ascanning electron micrograph of a side view of the fabric taken at 150×magnification is shown in FIG. 43. Scanning electron micrographs of sideviews of the fabric taken at 300× and 400× magnifications are shown inFIGS. 44 and 45, respectively. FIG. 45 clearly depicts the conforming ofthe fiber to the weave spacing, as the fiber has folded upon itself.

The length and width of the gaps between the fibers were about 0.08 mmand 0.02 mm, respectively. The fabric had a weight of 157 g/m².

A fiber (452 dtex) was removed from the woven fabric and dimensionalmeasurements were taken of its conformed state post-weaving in order todemonstrate the conformability of the fiber. The fiber had apost-weaving folded width of 0.50 mm, a post-weaving folded height of0.1219 mm, a post-weaving aspect ratio of 4.1, and a post-weavingdensity of 0.74 g/cm³. The pre-woven width to the post-weaving foldedwidth ratio was 4.4 to 1.

Comparative Example 1

An ePTFE fiber by W.L. Gore & Associates (part number V111776, W.L. Gore& Associates, Inc., Elkton, Md.) was obtained. The ePTFE fiber measured111 dtex and had a rectangular cross-section and possessed the followingproperties: width=0.5 mm, height=0.0114 mm, density=1.94 g/cm³, breakstrength=3.96 N, tenacity=3.58 cN/dtex, and fibril length=indeterminate(no visible nodes to define an endpoint for the fibrils). A scanningelectron micrograph of the top surface of the fiber taken at 1000×magnification is shown in FIG. 32. A scanning electron micrograph of aside view of the fiber taken at 1000× magnification is shown in FIG. 33.

In order to successfully weave this fiber, it was twisted at 315turns/meter. This twisted fiber was then woven into a fabric using a 2/2twill pattern and a thread count of 100×100 threads/inch.

The woven fabric had the following properties: thickness=0.12 mm,MVTR=36756 g/m²/24 hours, water pick-up=4 gsm, hand=102 g, WEP=0.39 kPa,air permeability=367 cfm, and oil rating=<1. A scanning electronmicrograph of the top surface of the fabric taken at 150× magnificationis shown in FIG. 34. A scanning electron micrograph of a side view ofthe fabric taken at 150× magnification is shown in FIG. 35. The lengthand width of the gaps between the fibers were about 0.09 mm and 0.12 mm,respectively. The fabric had a weight of 94 g/m².

Comparative Example 2

A non-microporous commercially available ePTFE fiber available from W.L.Gore & Associates (part number V112961, W.L. Gore & Associates, Inc.,Elkton, Md.) was obtained. The ePTFE fiber measured 457 dtex and had arectangular cross-section and possessed the following properties:width=0.6 mm, height=0.0419 mm, density=1.82 g/cm³, break strength=18.33N, tenacity=4.03 cN/dtex, and fibril length=indeterminate (no visiblenodes to define an endpoint for the fibrils). A scanning electronmicrograph of the top surface of the fiber taken at 1000× magnificationis shown in FIG. 46. A scanning electron micrograph of a side view ofthe fiber taken at 1000× magnification is shown in FIG. 47.

In order to successfully weave this ePTFE fiber, it was twisted at 118turns/meter. This twisted fiber was then woven into a fabric using aplain weave pattern and a thread count of 50×50 threads/inch.

The woven fabric had the following properties: thickness=0.21 mm,MVTR=11659 g/m²/24 hours, water pick-up=10 gsm, hand=380 g, WEP=0.49kPa, air permeability=70 cfm, and oil rating=<1. A scanning electronmicrograph of the top surface of the fabric taken at 150× magnificationis shown in FIG. 48. A scanning electron micrograph of a side view ofthe fabric taken at 150× magnification is shown in FIG. 49. The lengthand width of the gaps between the fibers were about 0.11 mm and 0.08 mm,respectively. The fabric had a weight of 201 g/m².

Comparative Example 3

A commercially available ePTFE fiber available from W.L. Gore &Associates (part number V112961, W.L. Gore & Associates, Inc., Elkton,Md.) was obtained. The ePTFE fiber measured 457 dtex and had arectangular cross-section and possessed the following properties:width=0.6 mm, height=0.0419 mm, density=1.82 g/cm³, break strength=18.33N, tenacity=4.03 cN/dtex, and fibril length=indeterminate (no visiblenodes to define an endpoint for the fibrils). A scanning electronmicrograph of the top surface of the fiber taken at 1000× magnificationis shown in FIG. 46. A side view of the fiber taken at 1000×magnification is shown in FIG. 47.

In order to successfully weave this ePTFE fiber, it was twisted at 138turns/meter. This twisted fiber was then woven into a fabric using aplain weave pattern and a thread count of 64×64 threads/inch.

The woven fabric had the following properties: thickness=0.24 mm,MVTR=7840 g/m²/24 hours, water pick-up=9 gsm, hand=698 g, WEP=1.12 kPa,air permeability=26 cfm, and oil rating=<1. A scanning electronmicrograph of the top surface of the fabric taken at 150× magnificationis shown in FIG. 50. A side view of the fabric taken at 150×magnification is shown in FIG. 51. The length and width of the gapsbetween the fibers were about 0.07 mm and 0.02 mm, respectively. Thefabric had a weight of 261 g/m².

The invention of this application has been described above bothgenerically and with regard to specific embodiments. It will be apparentto those skilled in the art that various modifications and variations ofthe invention can be made without departing from the spirit or scope ofthe invention, as defined in the appended claims.

What is claimed is:
 1. A woven fabric comprising: a plurality of warpfibers and weft fibers, each said warp fibers and each said weft fiberscomprising expanded polytetrafluoroethylene (ePTFE) fibers having asubstantially rectangular cross sectional configuration, wherein apre-woven width of said ePTFE fiber is greater than a width allotted tosaid ePTFE fiber based on an end count or pick count of said wovenfabric.
 2. The woven fabric of claim 1, wherein said ePTFE fibers aremonofilament fibers.
 3. The woven fabric of claim 1, wherein said ePTFEfibers have a density less than about 1.2 g/cm³.
 4. The woven fabric ofclaim 1, wherein said ePTFE fibers have a pre-weaving density less thanabout 0.85 g/cm³.
 5. The woven fabric of claim 1, wherein said ePTFEfibers have nodes and fibrils defining passageways through said fiber,and wherein said fibrils have a length from about 5 microns to about 120microns.
 6. The woven fabric of claim 1, wherein said woven fabric hasan air permeability less than about 5 cfm.
 7. The woven fabric of claim5, wherein said woven fabric has a moisture vapor transmission rategreater than about 10,000 g/m²/24 hours.
 8. The woven fabric of claim 1,wherein said woven fabric has a water pick-up less than about 30 gsm. 9.The woven fabric of claim 1, wherein said ePTFE fibers have an aspectratio greater than about
 15. 10. The woven fabric of claim 1, whereinsaid ePTFE fibers have a weight per length of less than about 500 dtex.11. The woven fabric of claim 1, wherein said woven fabric has anaverage stiffness of less than about 300 g.
 12. The woven fabric ofclaim 1, wherein said woven fabric has a weight per unit area of lessthan about 300 g/m².
 13. The woven fabric of claim 1, wherein said wovenfabric has a tear strength of at least 30 N.
 14. The woven fabric ofclaim 1, wherein said woven fabric has an average water entry pressuregreater than about 1 kPa.
 15. The woven fabric of claim 1, wherein saidwarp fibers and said weft fibers have a fluoroacrylate coating to rendersaid woven fabric oleophobic.
 16. The woven fabric of claim 15, furthercomprising a functional membrane affixed to said warp and said weftfibers on a side opposing said fluoroacrylate coating.
 17. The wovenfabric of claim 16, further comprising a textile affixed to saidfunctional membrane.
 18. The woven fabric of claim 15, furthercomprising a textile affixed to said warp fibers and weft fibers on aside opposing said fluoroacrylate coating.
 19. The woven fabric of claim1, further comprising at least one of a textile and a functionalmembrane affixed to said woven fabric.
 20. The woven fabric of claim 1,wherein said woven fabric is in the form of a garment, a glove, orfootwear.
 21. A woven fabric comprising: a plurality of warp fibers andweft fibers, each said warp fibers and said weft fibers comprisingexpanded polytetrafluoroethylene (ePTFE) fibers having a density lessthan about 1.2 g/cm³ and a substantially rectangular cross sectionalconfiguration.
 22. The woven fabric of claim 21, wherein said ePTFEfibers are monofilament fibers.
 23. The woven fabric of claim 21,wherein said woven fabric has a water entry pressure greater than about1 kPa.
 24. The woven fabric of claim 21, wherein said woven fabric has amoisture vapor transmission rate greater than about 10,000 g/m²/24hours.
 25. The woven fabric of claim 21, wherein said fabric has a waterpick-up less than about 30 gsm.
 26. The woven fabric of claim 21,wherein said fabric has a weight per unit area less than about 300 g/m².27. The woven fabric of claim 21, wherein at least one of said warp andweft fibers has an aspect ratio greater than about
 15. 28. The wovenfabric of claim 21, wherein said woven fabric has an air permeabilityless than about 5 cfm.
 29. The woven fabric of a claim 21, wherein eachsaid warp and said weft fibers have a pre-weaving thickness of less thanabout 100 microns and a pre-weaving width of less than about 4.0 mm. 30.The woven fabric of claim 29, wherein said width of said warp and saidweft fibers is greater than a width allotted to said expandedpolytetrafluoroethylene fibers based on an end count or a pick count ofsaid woven fabric.
 31. The woven fabric of claim 21, wherein saidexpanded polytetrafluoroethylene fibers have a pre-weaving density lessthan about 0.85 g/cm³.
 32. The woven fabric of claim 21, wherein saidwoven fabric has an average stiffness of less than about 300 g.
 33. Thewoven fabric of claim 21, wherein said woven fabric has a tear strengthof at least 30 N.
 34. The woven fabric of claim 21, wherein said warpfibers and said weft fibers have a fluoroacrylate coating to render saidwoven fabric oleophobic.
 35. The woven fabric of claim 34, furthercomprising a functional membrane affixed to said warp fibers and saidweft fibers on a side opposing said fluoroacrylate coating.
 36. Thewoven fabric of claim 35, further comprising a textile affixed to saidfunctional membrane.
 37. The woven fabric of claim 34, furthercomprising a textile affixed to said warp fibers and weft fibers on aside opposing said fluoroacrylate coating.
 38. The woven fabric of claim21, further comprising at least one of a textile and a functionalmembrane affixed to said woven fabric.
 39. The woven fabric claim 21,wherein said ePTFE fibers have a node and fibril structure definingpassageways through said fibers, said fibrils having a length from about5 microns to about 120 microns.
 40. The woven fabric claim 21, whereinsaid woven fabric is in the form of a garment, a glove, or footwear. 41.A woven fabric comprising: warp and weft fibers comprising expandedpolytetrafluoroethylene (ePTFE) fibers having a substantiallyrectangular cross-section configuration, wherein said woven fabric has awater entry pressure greater than about 1 kPa, and wherein said wovenfabric has a moisture vapor transmission rate greater than about 10,000g/m²/24 hours.
 42. The woven fabric of claim 41, wherein said ePTFEfibers are monofilament fibers.
 43. The woven fabric of claim 41,wherein a pre-weaving density of said expanded polytetrafluoroethylenefibers is less than about 0.85 g/cm³.
 44. The woven fabric of claim 41,wherein said warp and weft fibers have a pre-weaving thickness less thanabout 100 microns and a pre-weaving width less than about 4.0 mm. 45.The woven fabric of claim 44, wherein said width of said expandedpolytetrafluoroethylene fibers is greater than a width allotted to saidexpanded polytetrafluoroethylene fibers in said woven fabric based on anend count or pick count of said woven fabric.
 46. The woven fabric ofclaim 41, wherein said expanded polytetrafluoroethylene fibers areconformable such that in a woven configuration, said expandedpolytetrafluoroethylene fiber folds upon itself.
 47. The woven fabric ofclaim 41, wherein said woven fabric has an average stiffness less thanabout 300 g.
 48. The woven fabric of claim 41, wherein said woven fabrichas an air permeability less than about 5 cfm.
 49. The woven fabric ofclaim 41, wherein said woven fabric has a tear strength of at least 30N.
 50. The woven fabric of claim 41, wherein said woven fabric has anaverage water entry pressure greater than about 2 kPa.
 51. The wovenfabric of claim 41, wherein said fabric has a weight per unit area lessthan about 300 g/m².
 52. The woven fabric of claim 41, wherein said warpfibers and said weft fibers have a fluoroacrylate coating.
 53. The wovenfabric of claim 52, further comprising a functional membrane affixed tosaid warp fibers and said weft fibers on a side opposing saidfluoroacrylate coating.
 54. The woven fabric of claim 53, furthercomprising a textile affixed to said functional membrane.
 55. The wovenfabric of claim 52, further comprising a textile affixed to said warpfibers and said weft fibers on a side opposing said fluoroacrylatecoating.
 56. The woven fabric of claim 41, further comprising at leastone of a textile and a functional membrane affixed to said woven fabric.57. The woven fabric of claim 41 wherein said expandedpolytetrafluoroethylene (ePTFE) fibers have a node and fibril structuredefining passageways through said fibers, said fibrils having a lengthfrom about 5 microns to about 120 microns.
 58. The woven fabric of claim57, wherein said ePTFE fibers are monofilament fibers.
 59. The wovenfabric of claim 41, wherein said woven fabric is in the form of agarment, a glove, or footwear.
 60. A woven fabric comprising: warp andweft fluoropolymer fibers having a length and a width, at least one ofsaid warp and said weft fluoropolymer fibers being in a foldedconfiguration along said length of said fiber.
 61. The woven fabric ofclaim 60, wherein said woven fabric has a moisture vapor transmissionrate greater than about 10,000 g/m²/24 hours and a water entry pressuregreater than about 1 kPa.
 62. The woven fabric of claim 60, wherein saidfluoropolymer fibers have a weight per length of less than about 500dtex.
 63. The woven fabric of claim 60, wherein said fluoropolymerfibers have an aspect ratio greater than about
 15. 64. The woven fabricof claim 60, wherein said fluoropolymer fibers are conformable such thatin a woven configuration, said fluoropolymer fibers fold uponthemselves.
 65. The woven fabric of claim 60, wherein said fluoropolymerfibers are monofilament fibers having a porous microstructure.
 66. Thewoven fabric of claim 60, wherein said fluoropolymer fibers have nodesand fibrils defining passageways through said fiber, and wherein saidfibrils have a length from about 5 microns to about 120 microns.
 67. Thewoven fabric of claim 60, wherein said fluoropolymer fibers are expandedpolytetrafluoroethylene (ePTFE) fibers.
 68. The woven fabric of claim67, wherein said ePTFE fibers have a density less than about 1.2 g/cm³.69. The woven fabric of claim 67, wherein said ePTFE fibers aremonofilament fibers.
 70. The woven fabric of claim 67, wherein saidePTFE fibers have a pre-weaving density less than about 0.85 g/cm³. 71.The woven fabric of claim 67, wherein said width of said ePTFE fibers isgreater than a width allotted to said ePTFE fibers in said woven fabricbased on an end count or a pick count of said woven fabric.
 72. Thewoven fabric of claim 67, wherein said ePTFE fibers have a pre-weavingwidth less than about 4.0 mm and a pre-weaving thickness less than about100 microns.
 73. The woven fabric of claim 67, wherein said woven fabrichas a water pick-up less than about 30 gsm.
 74. The woven fabric ofclaim 67, wherein said ePTFE fibers have an aspect ratio greater thanabout
 15. 75. The woven fabric of claim 67, wherein said woven fabrichas an average stiffness of less than about 300 g.
 76. The woven fabricof claim 67, wherein said woven fabric has an air permeability less thanabout 5 cfm.
 77. The woven fabric of claim 67, wherein said woven fabrichas a weight per unit area of less than about 300 g/m².
 78. The wovenfabric of claim 67, wherein said warp fibers and said weft fibers have afluoroacrylate coating.
 79. The woven fabric of claim 78, furthercomprising a functional membrane affixed to said warp fibers and saidweft fibers on a side opposing said fluoroacrylate coating.
 80. Thewoven fabric of claim 79, further comprising a textile affixed to saidfunctional membrane.
 81. The woven fabric of claim 78, furthercomprising a textile affixed to said warp fibers and said weft fibers ona side opposing said fluoroacrylate coating.
 82. The woven fabric ofclaim 67, further comprising at least one of a textile and a functionalmembrane affixed to said woven fabric.
 83. The woven fabric of claim 67,wherein said ePTFE fibers have a break strength of at least about 1.5 N.84. The woven fabric of claim 67, wherein said fabric is in the form ofa garment, a glove, or footwear.
 85. A woven fabric comprising warp andweft fluoropolymer fibers having a node and fibril structure definingpassageways through said fiber, said fluoropolymer fibers beingmicroporous, wherein said woven fabric has an air permeability less thanabout 5 cfm and a moisture vapor transmission rate greater than about10,000 g/m²/24 hours.
 86. The woven fabric of claim 85, wherein saidfluoropolymer fibers are expanded polytetrafluoroethylene fibers. 87.The woven fabric of claim 87, wherein said expandedpolytetrafluoroethylene fibers have a pre-weaving density of less thanabout 0.85 g/cc.
 88. The woven fabric of claim 85, wherein said wovenfabric has a water entry pressure greater than about 1 kPa.
 89. Thewoven fabric of claim 85, wherein said fabric has a water pick-up lessthan about 30 gsm.
 90. The woven fabric of claim 85, wherein said fabrichas a weight per unit area of 300 g/m².
 91. The woven fabric of claim85, wherein at least one of said warp and weft fluoropolymer fibers hasan aspect ratio greater than about
 15. 92. The woven fabric of a claim85, wherein each said warp and said weft fluoropolymer fibers have apre-weaving thickness less than about 100 microns and a width less thanabout 4.0 mm.
 93. The woven fabric of claim 85, wherein said width isgreater than a width allotted to the fluoropolymer fiber based on an endcount or a pick count of said woven fabric.
 94. The woven fabric ofclaim 85, wherein said woven fabric has an average stiffness of lessthan about 300 g.
 95. The woven fabric of claim 85, wherein said wovenfabric has a tear strength of at least 30 N.
 96. The woven fabric ofclaim 85, wherein said fibrils have length from about 5 microns to about120 microns.
 97. The woven fabric of claim 85, further comprising atleast one of a textile and a fluoropolymer membrane affixed to saidwoven fabric.
 98. The woven fabric of claim 85, wherein said wovenfabric is in the form of a garment, a glove, or footwear.
 99. Amonofilament fiber comprising expanded polytetrafluoroethylene, saidmonofilament fiber having a density less than or equal to about 1.0g/cm³, a thickness less than about 100 microns, a width less than about4.0 mm, an aspect ratio greater than about 15, and a substantiallyrectangular cross-section configuration.
 100. The monofilament fiber ofclaim 99, wherein said monofilament fiber has a tenacity greater thanabout 1.6 cN/dtex.
 101. The monofilament fiber of claim 99, wherein saidmonofilament fiber has a break strength of at least about 1.5 N. 102.The monofilament fiber of claim 99, wherein said monofilament fiber hasthereon a fluoroacrylate coating.
 103. The monofilament fiber of claim99, wherein said monofilament fiber is conformable such that in a wovenconfiguration, said monofilament fiber folds upon itself.
 104. Themonofilament fiber of claim 99, wherein said monofilament fiber hasnodes and fibrils defining passageways through said fiber.
 105. Themonofilament fiber of claim 99, wherein said fibrils have a length fromabout 5 microns to about 120 microns.
 106. The monofilament fiber ofclaim 99, wherein said monofilament fiber has a weight per length ofless than about 500 dtex.